Touch screens that utilize capacitive sense arrays are widely applied in today's industrial and consumer product markets. Capacitive sense arrays can be found in cellular phones, GPS devices, set-top boxes, cameras, computer screens, MP3 players, digital tablets, and the like, replacing mechanical buttons, knobs, and other conventional user interface controls. A capacitive sense array is often disposed below a touch sensing surface of a touch screen, and includes an array of capacitive sense elements. Capacitances of these capacitive sense elements vary when an object (e.g., a finger, a hand, a stylus, or another object) comes into contact with or hovers above the touch sensing surface. A processing device coupled to the capacitive sense array then measures the capacitances of the capacitive sense elements and/or identifies capacitance variations of the capacitive sense elements for determining a touch or presence of the object associated with the touch sensing surface. The use of the capacitive sense array has offered a convenient and reliable user interface solution that is feasible under many harsh conditions.
Although capacitive sense arrays made of capacitive sense elements have been widely used in many industrial and consumer products, they oftentimes involve one or more dedicated touch sensing layers that are separate from other layers of materials used for display functions of a touch screen. It would be beneficial to integrate touch detection into existing display related infrastructure of a conventional touch screen without causing any detrimental impact on the display functions of the touch screen.